Create standalone browser port of LTX Athena with authenticated native API transport

frontend/lib/keyframe-strength.test.ts

@@ -0,0 +1,53 @@
+import assert from 'node:assert/strict'
+import { describe, it } from 'node:test'
+import {
+  DEFAULT_KEYFRAME_STRENGTH,
+  formatKeyframeStrength,
+  nudgeKeyframeStrength,
+  strengthFromPointer,
+} from './keyframe-strength.ts'
+
+describe('strengthFromPointer', () => {
+  const rail = { top: 10, height: 100 }
+
+  it('maps the top of the rail to full strength', () => {
+    assert.equal(strengthFromPointer(10, rail), 1)
+  })
+
+  it('maps the bottom of the rail to zero strength', () => {
+    assert.equal(strengthFromPointer(110, rail), 0)
+  })
+
+  it('maps the midpoint to 0.5', () => {
+    assert.equal(strengthFromPointer(60, rail), 0.5)
+  })
+
+  it('clamps above the rail to 1 and below it to 0', () => {
+    assert.equal(strengthFromPointer(0, rail), 1)
+    assert.equal(strengthFromPointer(200, rail), 0)
+  })
+
+  it('returns the new-still default when the rail has no height', () => {
+    assert.equal(strengthFromPointer(10, { top: 10, height: 0 }), DEFAULT_KEYFRAME_STRENGTH)
+  })
+})
+
+describe('nudgeKeyframeStrength', () => {
+  it('steps by five percent', () => {
+    assert.equal(nudgeKeyframeStrength(0.7, 1), 0.75)
+    assert.equal(nudgeKeyframeStrength(0.7, -1), 0.65)
+  })
+
+  it('clamps at 0 and 1', () => {
+    assert.equal(nudgeKeyframeStrength(0.02, -1), 0)
+    assert.equal(nudgeKeyframeStrength(0.98, 1), 1)
+  })
+})
+
+describe('formatKeyframeStrength', () => {
+  it('renders owned strength as a percent', () => {
+    assert.equal(formatKeyframeStrength(0.7), '70%')
+    assert.equal(formatKeyframeStrength(0), '0%')
+    assert.equal(formatKeyframeStrength(1), '100%')
+  })
+})